Electrical lead-through for pressure intensifier



A ril 12, 1966 A. E. SMITH 3,

ELECTRICAL LEAD-THROUGH FOR PRESSURE INTENSIFIER Filed Jan. 8, 1965 2 Sheets-Sheet 1 ////fi //////)4 /////Z INVENTOR. Alfred E. Smifh BY flawrw' ATTORNEY.

April 12, 1966 A. E. SMITH 3,245,118

ELECTRICAL LEAD-THROUGH FOR PRESSURE INTENSIFIER Filed Jan. 8, 1965 2 Sheets-Sheet 2 INVENTOR.

Alfred E. Smifh BY 5%...

ATTORNEY.

United States Patent 3,245,118 ELECTRICAL LEAD-THROUGH FOR PRESSURE INTENSIFIER Alfred E. Smith, Clinton, Tenn, assignor to the United States of America as represented by the United States Atomic Energy Commission Filed Jan. 8, 1965, Ser. No. 424,450 3 Claims. (CI. 18-16) The present invention relates to pressure intensifying devices generally and more particularly to an improved electrical lead-through for the movable or stationary piston of a piston-cylinder type high pressure intensifier.

Very high pressures have been utilized to effect material densification, phase transformations, and chemical changes. In many instances however, attainable pressures are insufiicient to produce the desired result. In other cases, the necessary pressure can be produced on very small samples only, making commercial application impractical or impossible where larger samples are required. An additional factor which must be considered when evaluating the desirability of applying high pressure, is the high cost of pressure intensifiers which increases exponentially with pressure for any given working volume.

In practically all instances where densification or chemical reactions are accomplished through the application of high pressures, a considerably lower pressure would be sufiicient if the temperature of the workpiece were raised. To accomplish such a rise in temperature, a resistance type heating element is normally used. Such a heating arrangement requires electrical leads which must pass through one of the pistons or the cylinder Wall in a piston-cylinder type pressure intensifier.

The passing of electrical leads from the outside of the pressure intensifier to its innermost high pressure cavity presents a difficult problem of preventing working fluid leakage about the leads or a complete lead blowout due to their lesser ability to sustain large pressure induced loads. When the electrical leads are used to supply resistance heaters within the pressure intensifier, the magnitude of the problem is increased due to the necessarily large cross section of the leads. A lesser problem exists where the leads are of the smaller size used for instrumentation. Leads of both types are typically used where heat is applied to the high pressure cavity. The severity of the roblem increases as the pressures developed Within the intensifier increase.

It is, accordingly, a general object of the invention to provide improved means for admitting electrical leads to the interior of a pressure intensifier.

Another object of the invention is to provide improved means for admitting electrical leads to the interior of a pressure intensifier which is applicable to either the movable or stationary piston thereof.

Other objects of the invention will become apparent from an examination of the following description of the invention and the accompanying drawings, wherein:

FIG. 1 is a vertical sectional view of a piston-cylinder type pressure intensifier incorporating the invention.

FIG. 2 is an enlarged isometric view, partly in section, of the movable piston 3 shown in FIG. 1.

FIG. 3 is an enlarged transverse section of the movable piston 3 shown in FIGS. 1 and 2.

In accordance with the present invention, an improved means for admitting electrical leads to the interior of a piston-cylinder type pressure intensifier is provided. A piston member of the intensifier, which sealably engages the cylinder wall through the use of O-rings, is provided with longitudinal tapered slots equally spaced about its periphery. Into each slot a wire conductor is potted with an epoxy mix acting as potting agent. The potted wires 3,245,118 Patented Apr. 12, 1966 ice are then covered by an elongated tapered plug which fills the slot and is dove-tailed into the sides thereof.

To facilitate an understanding of the invention, reference is first made of FIG. 1 of the accompanying drawings wherein a preferred embodiment of the invention is illustrated. FIG. 1 depicts a piston-cylinder type pressure vessel comprising a multi-walled cylinder 1, a fixed piston 2 and a movable piston 3. Cylinder 1 and fixed piston 2 rest on a rigid support 11. Pistons 2 and 3 sealably engage the interior wall of cylinder 1 with O-rings 4. In order to simplify the present discussion, the invention is described and illustrated herein as applied to the movable piston only. It will be apparent to those skilled in the art that the method described herein may be readily applied to passing electrical leads through the stationary piston also where the problem is not as difficult. It will also be apparent that where a large number of leads must be admitted to the interior of the pressure intensifier, the present invention could be used in passing the leads through both the movable and stationary pistons at the same time.

FIG. 2 illustrates with greater clarity the various features of movable piston 3. As may be seen in FIG. 2, the piston 3 is an elongated solid cylinder. Four longitudinal slots 5, tapered along their lengths, are provided at equally spaced intervals about the circumference of piston 3. These slots 5 extend from the interior end 6 of piston 3 which is fitted into mating cylinder 1 to a point along the length of piston 3 which is never inserted into cylinder 1, so that during a pressing operation, one end of each slot 5 will be within cylinder 1 while the other end will be outside the cylinder. The distance which slots 5 extend along the side of piston 3 normally exceeds one-half of its length.

One or more electrically conductive wires 7 (two shown) are placed in the bottom of each slot 5 and potted in place with an epoxy mix 8 which functions to secure the wires 7 in place and electrically insulate them.

A tapered plug 9 is force-fitted into each slot 5, using about 200,000 p.s.i. thereby covering the epoxy held wires 7 and filling slot 5 flush with the circumference of piston 3. Each plug 9 is dovetailed longitudinally into the sides of each slot 5 and is provided with a T shaped end 10 which assists in preventing movement of plug 9 when its end 10 is subjected to pressures of 200,000 p.s.i. or greater during use. The projecting end 10 of each plug 9 also serves to prevent damage to Wires 7 where they exit from between piston 3 and plug 9. As further protection, the entire end 6 of piston 3 is potted with epoxy.

Circumferential-ring grooves 12 are provided adjacent end 6 of piston 3. O-rings 4 (only one of two shown) inserted in these grooves serve to seal piston 3 within its mating cylinder 1. Wires 7, epoxy 8, and plug 9 do not interfere in any way with the sealing capacity of O-rings 4 nor do they interfere with the functioning of piston 3 as it is slid in and out of cylinder 1 during use.

FIG. 3 supplements FIGS. 1 and 2 in illustrating the manner in which tapered plugs 9, wires 7, and epoxy mix 8 are disposed within slots 5 of piston 3. The dovetailed fit of tapered plugs 9 in slots 5 and the manner in which wires 7 are supported and insulated by epoxy mix 8 are clarified.

The above description of one form of the invention was offered for illustrative purposes only, and should not be interpreted in a limiting sense. For example, the invention could be readily applied to the stationary as well as the movable piston of a piston-cylinder type pressure intensifier. In addition, the number of electrical leads and slots therefore may be varied from the eight leads and four slots illustrated. For this reason, it is intended that the invention be limited only by the claims appended hereto.

What is claimed is:

1. The improved means for passing electrical leads into the interior cavity of a piston-cylinder type pressure intensifier comprising: a piston member having at least one longitudinally tapered slot along its periphery, at least one electrical conductor passing along the bottom of said slot, an epoxy mix disposed within and partially filling said slot, said epoxy mix electrically insulating and supporting said electrical conductor while sealing said slot, and an elongated tapered plug covering said slot and said epoxy mix, said plug being dove-tailed longitudinally into the sides of said slot.

2. The improved means for passing electrical leads into the interior cavity of a piston-cylinder type pressure intensifier comprising: a piston member having at least one longitudinally tapered peripheral slot beginning at its interior end and extending along its side, at least one electrical conductor passing along the bottom of said slot, an epoxy mix disposed within and partially filling said slot, said epoxy mix electrically insulating and supporting said electrical conductor while sealing said slot, and an elongated plug tapered identically with and dovetailed longitudinally into the sides of said slot, said plug having a T-shaped end engaging the interior end of said piston member.

3. In a piston-cylinder type pressure intensifier wherein a movable piston slidably and sealably engages the interior surface of a hollow cylinder, the improved system for passing electrical leads into the interior cavity of said pressure intensifier comprising: said piston member having at least one longitudinally tapered peripheral slot, said slot beginning at the interior end of said piston and extending to a point along the side of said piston which is never inserted into said cylinder, at least one electrical conductor passing along the bottom of said slot, an epoxy mix disposed within and partially filling said slot to insulate and support said electrical conductor while sealing said slot, and an elongated plug tapered identically with and dove-tailed longitudinally into the sides of said slot, said plug having a T-shaped end engaging the interior end of said piston member.

No references cited.

LARAMIE E. ASKIN, Primary Examiner. 

1. THE IMPROVED MEANS FOR PASSING ELECTRICAL LEADS INTO THE INTERIOR CAVITY OF A PISTON-CYLINDER TYPE PRESSURE INTENSIFIER COMPRISING: A PISTON MEMBER HAVING AT LEAST ONE LONGITUDINALLY TAPERED SLOT ALONG ITS PERIPHERY, AT LEAST ONE ELECTRICAL CONDUCTOR PASSING ALONG THE BOTTOM OF SAID SLOT, AN EPOXY MIX DISPOSED WITHIN AND PARTIALLY FILLING SAID SLOT, SAID EPOXY MIX ELECTRICALLY INSULATING AND SUPPORTING SAID ELECTRICAL CONDUCTOR WHILE SEALING SAID SLOT, AND AN ELONGATED TAPERED PLUG COVERING SAID SLOT AND SAID EPOXY MIX, SAID PLUG BEING DOVE-TAILED LONGITUDINALLY INTO THE SIDES OF SAID SLOT. 